We have one of these and whilst getting a 'clock fail' fail message for a while, we also had to keep powering it down and up again each morning to clear a GFI error, and to get it to start generating. We've replaced the battery with the help of aurora power one inverter - https://www.electriciansforums.co.uk/threads/aurora-power-one-inverter.108599/ and set the time and date manually - and so far for three days all has been good and not needed to manually reset it, it is again working as is should. Installation company has gone out of business and the unit is out of warrantee by a few months. Thanks to google and it's link to this forum seems we've solved the problem - Thanks!